Lightning arrester



2 Sheets-Sheet 1 ATTORNE F5 x. REES ETAL LIGHTNING ARRESTER Fi led Sept.27, 1940 Sept. 29, 1942.

Sept. 29, 1942. F. x. REES ETAL' 2,297,323

LIGHTNING ARRESTER Filed se i'. 27, 1940 2 Sheets-Sheet 2 ATTOR EYPatented Sept. 29, 1942 LIGHTNING ARRESTER Frank Xavier Rees, Albany, N.1., and Frederick C. Lavarack, Montclalr, N. 1., More to BailroadAccessories Corporation, New York, N. Y., a corporation of New YorkApplication September 27, 1940, Serial No. 358,626

9 Claims.

This invention relates to lightning arresters.

A principal object of the invention is the production of a device of thetype specified which is constructed on such principles that it mayoccupy the minimum of space and at the same time exhibit highefficiency.

A further object of this invention is to provide a device of the typespecified which may be manufactured in such manner that it may be aninch or less in width and an inch and threeeighths or less in length andrelatively short and of such efiiciency that it will amply and properlyprotect, from damage by lightning, railroad signal apparatus connectedto aerial conductors.

A further object of the invention is the production of a device of thetype specified which is provided with discharge teeth of such acutenessthat when a point thereof is melted the molten metal will tend to runback on the teeth.

A further object of the invention is the production of a device of thetype specified which is constructed with a plurality of discharge teethwhich are spaced apart such a distance that when the teeth are properlypositioned facing a discharge surface, the arcon one tooth will not burnan adjacent tooth.

A further object of the invention is the production of a device of thetype specified which is so constructed that when the discharge teeththereof are properly positioned facing a discharge surface, an are fromone point will not ionize the gap between an adjacent point and thedischarge surface thus causing that point to also discharge as the firstmentioned point burns back increasing the gap and thereby the voltageacross it and the two low resistance bodies.

. A further object of the invention is the production of a device of thetype specified in which the discharge points are sufliciently closelyadjacent to a high resistance body in contact with a discharge plate asto start ionization of the air at a comparatively small voltage and yet,due to the high resistance body, obviate any danger .of a complete shortcircuit.

A further object of the invention is the production of a device of thetype specified in which the discharge points are sufficiently closelyadjacent to a high resistance body in contact with a discharge plate asto start ionization of the air at a comparatively low voltage and yet,due to the high resistance body which serves no part in maintaining anestablished arc, provides the same are extinguishing ability as thoughthe high resistance body were not present.

Other objects and advantages of the invention will appear as thedescription of the particular physical embodiment selected to illustratethe invention progresses and the novel features will be particularlypointed out in the appended claims.

jln describing the invention in detail and the particular physicalembodiment selected to illustrate the invention, reference will be hadto the accompanying drawings and the several views thereon, in whichlike characters of reference designate like parts throughout the severalviews, and in which:

Figure 1 is a side elevational view of a device embodying the inventionmounted on a terminal block which is shown in section; Fig. 2 is acrosssectional view of the device, as shown by Fig. 1 in plan, on theplane indicated by the line 11-]:[, viewed in the direction of thearrows at the ends of the line but with a portion of the end connectionblock broken away; Fig. 3 is a cross-sectional view of the device, asshown by Fig. l, on the plane indicated by the line III-I11, viewed inthe direction of the arrows at the ends of the line; Fig. 4 is across-sectional view of the device, as shown by Fig. 3, on the planeindicated by the line IVIV, viewed in the direction of the arrows at theends of the line; Fig. 5 is a bottom plan view of the lightning arresterof applicants invention as shown applied to a terminal block in Fig. 1;Fig. 6 is a cross-sectional view of the device as shown by Fig. 4 on theplane indicated by the line VIVI, viewed in the direction of the arrowsat the ends of the line;'Fig. '7 is a bottom plan view of a cover usedwith applicants device,

as shown by Fig. 1; Fig. 8 is a perspective view of a metallic connectorused in applicants device, as shown by Fig. 1.

A lightning arrester embodying applicants principle is preferably madein a for in which there is a;. complete circle of discharge points.

- It is not to be inferred that the principles may not be embodied in anarrester of non-circular form but the preferred construction which givesthe maximum of discharge Points in a minimum of space embodies thecircular form.

Applicants invention, in its preferred form, includes a cup I of lowresistance material, preferably metal and preferably nickel-silver. Thiscup has an internal diameter such that it just receives a cylindricalprism 2 with a portion of the prism protruding beyond the free edge 3 ofthe cup. The cylindrical prism 2 is made of a high resistance materialand preferably a highly refractive material such as carborundum orEverohn.

Juxtaposed to the metallic cup I is the metallic cup 4 which has thesame internal diameter as the cup I and is made, preferably, of the samematerial but its free edge is formed into a series of teeth as 5. Theends of the points of these teeth are positioned substantially in theplane of the outer face of the high resistance body 2.

An insulating spacer t is provided. This spacer is shown as a disc andis made not only of insulating material but preferably of a refractoryinsulating material such as lava and is interposed between the metalliccup 4 and the high resistance body 2 so that the cups l and 4 can onlyapproach each other to such an extent as to position the points of teethof the cup 4 in the position hereinbefore stated;

. The members I, 2, 4 and 6 are each provided with an axial bore andwithin these bores is v ositioned a pin I which positions all of theBarts as shown most clearly in Fig. 3. This pin 1 is made of aninsulating material and preferably of lava.

In order to connect electrically to the cup bearing the discharge points5 and to the cup I, terminal connectors 8 and 8 are provided, shown inperspective in Fig. 8. Each of these terminal connectors is providedwith a through bore 9' and with presser fingers l and with a tail l Iprovided in any suitable or appropriate manner with convenient means forinsertion under a bolt, as by a cut out portion I2. Each of theseterminal connectors is identical in form but is reversely positionedwhen assembled, as shown in Fig. 3, as one tail extends outwardly in onedirection and the other one extends outwardly in the opposite direction,as best shown in Fig. 1.

A cover in the form of a hollow prism I3 is provided and the parts I, 2,4 and I together with the terminal connectors are positioned within theprism by first placing the ends of the pin 1 within the bores 9 of theterminal connectors and then pushing the whole assembly into the hollowprism l3 so that the parts rest in the position as shown in Fig. 3, thefingers I0 pressing against the inside surface of the hollow prism onopposite sides thereof to hold all parts in position and withoutshifting.

After the parts are positioned as described. it is best to provide aclosing plate I4, as best shown in Figs. 3 and 4 and to run ininsulating compound l5 to seal although there is still left anopportunity for any gases generated within the hollow prism to escapealong the channels 16 and IT.

The complete device is usually positioned on a connecting block I8, asshown in Fig. l, the connector 9 being placed under the nuts of one postI9 and the connector 8 under the nuts of the other post 20. The post I9is the post which is normally connected to ground by means of aconductor such as 2|. The post 20 is assumed to connect with an aerialconductor by means of the eyelet 22 and post 20 is connected to post 23by a conductor 24. The post 23 is connected in any suitable orappropriate manner with electrical apparatus.

The points of the teeth 5 are very closely adjacent the outside cornerof the member 2 but are not in contact therewith although if they doactually get in contact with member 2 the circuit formed would be ofsuch lngh resistance, due to the high resistance of the member 2, thatno great harm would result. The teeth 5 are made quite acute, that is,the included angle of the teeth is not greater than 45 degrees. In theparticular form now being built the angle is about 42 degrees and 30minutes. Teeth formed with such a small included angle are quiteessential because when the point of such a tooth is melted as by anelectrical discharge, the slight amount of metal melted will tend to wetand fiow back on the tooth itself without forming a. pendant globule.However, if molten metal at the point of a tooth does form into aglobule it will increase the distance between the tooth and the member 2rather than decrease it. 1

The teeth 5 are also spaced apart. In fact, in a preferred form of theinvention actually built, the points of the teeth are spaced apart morethan four times the distance between the ends of the teeth I and thefree edge 2 of the cup I so that an arc formed between a tooth and thefree edge I of the cup I will not Jump to an adjacent tooth.Furthermore, an are between one tooth and the free edge of the cup iwill not burn an adjacent tooth. In an actual device, the cup 4 has beenmade 0.841 inch in internal diameter and the teeth on the free edgethereof have been made 0.125 inch at their base and 0.160 inch in lengthso that 16 of them were positioned around the free edge of the cup 4.

The teeth 5 are positioned almost touching the prism 2 so that arelatively low voltage lightning potential will cause a discharge acrossthe exposed surface of 2 and will thus ionize the surrounding air so asto aiford a lower resistance path and thus act to start the arc before adifference of potential applied across the cups has arisen to its fullvalue.

It will be seen that under no contingency can the resistance of the pathbetween cup 4 and cup I be substantially lowered because the breakdownvoltage between I and 4 is determined by the closest tooth 5 and if thatis partially destroyed then the breakdown voltage is deter mined by thenext closest tooth and the destruction of tooth after tooth tends toincrease the breakdown voltage rather than to decrease it and in thesame way if a. tooth becomes mutilated by reason of the point meltingthe breakdown voltage between that tooth and the cup is not decreasedbut increased.

Although applicants have particularly described the lightning arresterin a form in which the discharge takes place between the plate and acircle of points, it is to be understood that the principle in formingthe teeth are no more applicable to the circular form than they are to astraight line form.

Although we have particularly described one particular physicalembodiment of our invention and explained the operation, constructionand principle thereof, nevertheless, we desire to have it understoodthat the form selected is merely illustrative, but does not exhaust thepossible physical embodiments of the idea of means underlying ourinvention.

What we claim as new and desire to secure by Letters Patent of theUnited States, is:

l. A lightning arrester, including, in combination: a relatively highresistance body; a relatively low resistance body bearing against thehigh resistance body and extending partially thereacross; a secondrelatively low resistance body juxtaposed to the first mentionedrelatively low resistance body and the relatively high resistance bodyand parallel thereto, the said second relatively low resistance bodypresenting a toothed edge, the points of the teeth being just out ofcontact with the relatively high resistance body and facing the firstsaid low resistance body on the uncovered side of the high resistancebody, the included angle at the point of each tooth being less than 45degrees whereby when the point of a tooth is melted the molten metalwill have a tendency to run back on the tooth without forming asubstantial pendant globule and whereby the destruction of any number ofteeth cannot result in decreasing the resistance of the path between lowresistance bodies or between the second mentioned low resistance bodyand the relatively high resistance body and whereby upon the applicationof a high difference of potential between the low resistance bodies, apath of lower resistance is created by an initial ionization of the airtherebetween by a preliminary discharge along the surface of therelatively high resistance body, providing a low bolt breakdown, yethigh are extinguishing ability with obviation of a complete shortcircuit of the device'should the air gap become closed.

2. A lightning arrester, including, in combination: a relatively highresistance body; a relatively low resistance body bearing against thehigh resistance body and extending partially thereacross; a secondrelatively low resistance body juxtaposed to the first mentionedrelatively low resistance body and the relatively high resistance bodyand parallel thereto, the said sec ond relatively low resistance bodypresenting a toothed edge, the points of the teeth being just out ofcontact with the relatively high resistance body and facing the firstsaid low resistance body on the uncovered side of the high resistancebody, the included angle at the point of each tooth being less than 45degrees whereby when the point of a tooth is melted the molten metalwill have a tendency to run back on the tooth without forming asubstantial pendant globule and whereby the destruction of any number ofteeth cannot result in decreasing the resistance of the path between lowresistance bodies or between the second mentioned low resistance bodyand the relatively high resistance body and whereby upon the applicationof a high difference of potential between the low resistance bodies, apath of lower resistance is created by an initial ionization of the airtherebetween by a preliminary discharge along the surface of therelatively high resistance body, the said teeth being spaced apart adistance sumcient to prevent arcing at one tooth point from ionizing thegap of an adjacent tooth, allowing it also to discharge and therebydamaging more than one tooth in case of an extra heavy discharge.

3. A discharge plate for an arrester formed of relatively highconducting material in the form of a cylindrical cup, the free edge ofwhich is formed into a plurality of substantially equally spaced teeth,each tooth formed with an included angle of less than 45 degrees.

4. A discharge plate for an arrester formed of relatively highconducting material in the form of a cylindrical cup. the free edge ofwhich is formed into a plurality of substantially equally spaced teeth,each tooth formed with an included angle of such. acuteness that uponthe point of the tooth being melted the molten metal will all run backon the tooth.

5. A discharge plate for an arrester formed of relatively highconducting material in the form of a cylindrical cup, the free edge ofwhich is formed into a plurality of substantially equally spaced teethand the point of the teeth spaced apart more than four times thedistance at which the ends 01' the points are adapted to be spaced fromand to cooperate with a discharge body of high conductivity.

6. A lightning arrester, including in combination: a cylindrical prismof relatively high resistance material; a cylindrical cup of relativelylow resistance material, said cup of an internal diameter substantiallyequal to the external diameter of the prism and said cup receiving saidprism with a portion of the prism protruding therefrom, a secondcylindrical cup of low resistance material, said second cup of aninternal diameter substantially equal to that of the first cup and thefree edge of said second cup toothed, means for positioning said cups onan axis passing through the central portion of the bases thereof withthe teeth of the second cup presented toward the first cup and thepoints thereof in substantially the plane of the outer base of theprotruding prism.

7. A lightning arrester, including, in combination: a cylindrical prismof relatively high resistance formed with a through axial bore, acylindrical cup of relatively low resistance material formed with anaxial bore in its base, said cup of an internal diameter substantiallyequal to the external diameter of the prism, and said cup receiving saidprism with a portion of the prism protruding therefrom, a secondcylindrical cup of low resistance material, said second cup of aninternal diameter substantially equal to that of the first cup, the freeedge of the second cup toothed and an axial bore in the base thereof, aspacer of insulating material formed with an axial bore, and a pin ofinsulating material passing through the axial bore of each of the saidcups and prisms, the spacer'being of such thickness and so placed thatthe points of the teeth of the toothed cup are positioned substantiallyin the plane of the outer base of the high resistance prism.

8. A lightning arrester, including, in combination: a cylindrical prismof relatively high resistance formed with a through axial bore, acylindrical cup of relatively low resistance ma-v terial formed with anaxial bore in its base, said cup of an internal diameter substantiallyequal to the external diameter of the prism, and said cup receiving saidprism with a portion of the prism protruding therefrom, a secondcylindrical cup of low resistance material, said second cup of aninternal diameter substantially equal to that of the first cup, the freeedge of the second cup toothed and an axial bore in the base thereof, aspacer of insulating material formed with an axial bore, and a pin ofinsulating material passing through the axial bore of each of the saidcups and prisms, the spacer being of such thickness and so placed thatthe points of the teeth of the toothed cup are positioned substantiallyin the plane of the outer base of the high resistance prism, and meansfor electrically connecting to each cup.

9. A lightning arrester connector including, in combination: a hollowsubstantially right prism; two metallic connectors formed of sheetmetal, each provided with a bore, one connector positioned on one sideof the inside of the hollow prism and the other on the opposite side ofthe inside of the hollow prism; each connector formed with a connectingtail extending one in one direction from the hollow prism and the otherin the nector.

FRANK XAVIER REES. FREDERICK-C. LAVARACK.

